VAAL UNIVERSITY OF TECHNOLOGY
FACULTY OF APPLIED AND COMPUTER SCIENCES DEPARTMENT DEPARTMENT OF PHYSICS & NON-DESTRUCTIV NON-DESTRUCTIVE E TESTING nd
SUBJECT
: PHYSICS 1 (2 OPPORTUNITY)
CODE
: APFSG 1A
DATE
: JUNE/JULY 2016
DURATION
: 2 HOURS
EXAMINERS MODERATOR
: Mr. G.S. NKOSI : Mr. M.L. MBANDEZI
MARKS: TOTAL MARKS : 108 FULL MARKS : 100
INSTRUCTION: 1. 2. 3. 4.
Answer all questions. Question can be answered in any order, but subsections must be kept together. Non-Programmable calculators may be used. When doing calculations, give the final answer to at least two decimal places .
This question paper consists of 8 - typed pages, including Information sheet, and Front Page.
DO NOT TURN THIS PAGE BEFORE PERMISSION IS GRANTED
PHYSICS 1
APFSG1A”
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2nd OPPORTUNITY
2016 – JUNE/JULY JUNE/JULY - EXAM
QUESTION 1: MULTIPLE CHOICE [UNIT 1 – 19] [3 x 10 = 30] Write the correct answer for each of the following in your answer book. (Example 1.1. A) 1.1. The two hot-air balloons balloons in the drawing drawing are 48.2 m and 61.0 m above the ground. ground. A person in the left balloon observes that the right balloon is 13.3° above the horizontal. What is the horizontal distance x between between the two balloons?
A. B. C. D. E.
54.15 m 2.960 m 0.019 m 208.8 m 264.2 m
1.2. A ball is thrown vertically verticall y upward from the surface of the earth. Consider the following quantities: (1) the speed of the ball;
(2) the velocity of the ball;
(3) the acceleration of the ball.
Which of these is (are) zero when the ball has reached the maximum height? A. B. C. D. E.
1 and 2 only 1 and 3 only 1 only 2 only 1, 2 and 3
1
PHYSICS 1
1.3.
APFSG1A”
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2nd OPPORTUNITY
2016 – JUNE/JULY JUNE/JULY - EXAM
Note the following situations:
In which case will the magnitude of the normal force on the block is greatest? A. B. C. D. E.
Case 1. Case 2 . Case 3. Case 1 and 3 All the same
1.4. Which would would cause a more serious serious burn: 30 g of steam or 30 g of liquid water, water, both at 100°C; and why is this so? A. B. C. D. E.
Water, because itit is denser than steam. steam. The Steam, because of its specific heat capacity. Steam, because of its its latent latent heat of vaporization. vaporization. Water, because because its its specific heat is greater than that that of steam. steam. Either one would would cause cause a burn of of the same severity severity since they are both at the same same temperature.
1.5. The speed of sound in a certain string is 3.00 x 10 3 m/s. The graph shows the amplitude (in meters) of a wave travelling travelling through through the string string versus time (in seconds). seconds). What is the wavelength of this wave? 1 ) m (
0 0.5 1.5 2.5 3.5 4.5
t (s)
– 1
A. B. C. D. E.
0.5 cm 1.5 m 6.0 km 1.5 mm 6.0 m
2
PHYSICS 1
APFSG1A”
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2nd OPPORTUNITY
2016 – JUNE/JULY JUNE/JULY - EXAM
1.6. Which one of the following is not an example of convection? convection ? A. B. C. D. E.
Smoke rises above above a fire An eagle soars on an upraft of wind A person gets sunburn on the beach Water cooks spaghetti Electric heater warms a room
1.7. Two uncharged, conducting spheres, A and B, are held at rest on insulating stands and are in contact. A positively charged rod is brought brought near sphere sphere A as suggested suggested in in the figure. While the rod is in place, sphere B is moves away from A. How will will the spheres spheres be charged, if at all ?
A. B. C. D. E.
Sphere A
Sphere B
Positive Negative Positive Not charged Positive
Positive Positive Negative Negative Not charged
+
A
B
1.8. The nucleus nucleus of an atom has a radius of of 6.0 10 –15 m. If the nucleus contains contains 45 protons, how many neutrons does the t he nucleus contain? A. B. C. D. E.
45 80 170 19 125
1.9. Which one of of the following following statements concerning electromagne electromagnetic tic waves is false? A. B. C. D. E.
Electromagnetic Electromagnetic waves carry energy. energy. X-rays have longer wavelengths than radio waves. In vacuum, all electromagnetic electromag netic waves travel at the same speed. Lower frequency electromagnetic electromagnet ic waves can be produced by oscillating circuits. They consist of mutually perpendicular perpendicular electric fields and magnetic fields.
1.10. A bus leaves Johannesburg, takes a non-direct route and arrives in Cape Town 23 hours, 46 minutes later. If the distance between between the two cities is 1250 km, what what is the magnitude of of the bus' average velocity? A. B. C. D. E.
37.2 km/h 41.4 km/h 54.3 km/h 52.6 km/h 53.3 km/h 3
PHYSICS 1
2nd OPPORTUNITY
APFSG1A”
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2016 – JUNE/JULY JUNE/JULY - EXAM
QUESTION 2: LEARNING UNIT 1 – 7 [25] 2.1. Explain the total internal reflection.
[3]
2.2. The graphs below show a wave wave on a string moving moving in the negative negative x-direction. The mass per per -2 unit length of this wave is 1.2 x 10 kg/m. 6
6
4
4
2
2
) m 0 ( y
) m 0 ( y
0
1
2
3
4
5
-2
-2
-4
-4
-6
-6
x(m)
0
1
2
3
4
5
t(s)
Calculate the following: a. b. c. d. e. f. g. 2.3
Amplitude Wavelength Period Frequency Speed Tension in the rope The mathematical mathematic al equation of the wave
[1] [1] [1] [1] [2] [2] [2]
When one person person shouts shouts at a soccer soccer match, the sound intensity intensity level at the center of the field field is 60 dB. When all the people shout together, the intensity level increases to 109 dB. Assuming that each person generates the same sound intensity at the center of the field, how many people are at the match? [4]
2.4. Two loudspeakers loudspeakers 42.0 m apart and facing each each other emit identical identical 115 Hz sinusoidal sinusoidal sound waves that are exactly out of phase. Suzan is walking along a line between the speakers. As she walks, she finds herself moving through loud and quite spots. If Suzan stands 19. 19 .5 m from one speaker, is she standing at a quiet spot or a loud spot? Assume that the speed of s ound is 345 m/s. [4] 2.5. Astronomers have discovered discovered a planetary planetary system orbiting orbiting the star Upsilon Andromedae, Andromedae, which which 17 is at a distance of 4. 4.2 x 10 m from the earth. One planet is believed to be located at a 11 distance of 1. 1.2 x 10 m from fr om the star. Using visible light with a vacuum wavelength of 550 nm, what is the minimum necessary aperture diameter that a telescope must have so that it can resolve the planet and the star? [4] 4
PHYSICS 1
2nd OPPORTUNITY
APFSG1A”
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2016 – JUNE/JULY JUNE/JULY - EXAM
QUESTION 3: LEARNING UNIT 8 – 12 [24] 3.1.
State the Principle of conservation of Linear momentum (in words)
[3]
3.2.
The magnitudes of the four displacement vectors shown in the drawing are A = 16.0 m, B = 11.0 m, C = 12.0 m, and D = 26.0 m. Determine the magnitude and directional angle for the resultant that occurs when these vectors are added together. [7]
3.3.
A log log is floating on swiftly moving water. A stone stone is is dropped dropped from rest from an 80. 80 .0m bridge and lands on the log as it passes under the bridge. If the log moves with a constant speed of 8.0 m/s, what is the horizontal distance between the log and the bridge when the stone is released? [4]
3.4.
The figure below shows a block of of mass of 0.35kg 0.35kg which which is is released released from rest at a height of 3.0m above a horizontal surface. The block slides along the side of a horizontal circular hoop of radius R. What is the speed of the mass at the bottom of the hoop? [3]
3.5. A 0.3 kg bullet of of mass is fired horizontal horizontally ly at a constant speed speed of 65m/s 65m/s into a stationary wooden block of mass M = 15kg. The bullet bullet instantaneously instantaneously comes to rest in the block. block. The block with the embedded bullet slides along a horizontal surface with a coefficient of kinetic friction, µk = 0.125. Determine: initial v0
final
M
s
a. The take-off speed of the block with embedded bullet. b. How far the block with embedded bullet slides before they come to rest. 5
[2] [5]
PHYSICS 1
APFSG1A”
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2nd OPPORTUNITY
2016 – JUNE/JULY JUNE/JULY - EXAM
QUESTION 4: LEARNING UNIT 13 – 19 19 [29] 4.1. Define radiation
[2]
4.2. Two charges are placed placed relative to each other other as shown shown in the sketch: sketch: 2 C
-5 C
50 cm
2 cm
•
P
a. b.
Calculate the total electric field at point P. [4] Calculate the amount amount of of work work done by electrostatic force as 2 C charge on the drawing is moved to point P. [4] 4.3. The current in the 8 Ω resistor in in drawing is 0.50 A.
a. b.
Calculate the equivalent equivalent resistance in the circuit. Calculate the voltage across the battery?
[4] [4]
4.4.
A force of of 250 N is applied applied to a hydraulic jack piston piston that is is 0.01 m in diameter. If the piston that supports the load has a diameter of 0.10 m, approximately how much mass can be lifted by the jack? Ignore any difference in height between the pistons. [4]
4.5.
The coefficient of linear expansion of aluminum aluminum is 23 x 10 6/C°. A circular hole in an aluminum plate plate is 2.725 cm in diameter diameter at 0 °C. °C. What is the diameter of of the hole if the temperature of the plate is raised to 100 °C? [3]
4.6.
A sample contains 1000 nuclei of a radioactive isotope of barium. Exactly sixty seconds later, 970 nuclei in the sample have decayed. Determine the half-life of this isotope. [4]
__________________ ___________________________ ________________ _______ END ___________ _____________________ ___________________ __________________ _________
6
PHYSICS 1
2nd OPPORTUNITY
APFSG1A”
“
2016 – JUNE/JULY JUNE/JULY - EXAM
INFORMATION SHEET Acceleration Acceleration due to gravity Universal Gravitational constant Density of water Weakest audible sound Coulomb’s constant Speed of light Conversion factor Hydrogen atomic mass Neutron atomic mass Area of circle Atmospheric Atmospheri c Pressure Specific Heat Capacity of ice Specific Heat Capacity of Glass Specific Heat Capacity of water Latent Heat of fusion Latent Heat of Vapour Refractive Index of Water Refractive Index of Air
-2
: : : : : : : : : : : : : : : : : :
g = 9.80 m.s -11 2 2 G = 6.672 x 10 N.m /kg 3 -3 Water = 1.00 x 10 kg.m . -12 2 Io = 1.00 x 10 W/m 9 2 -2 k = 8.99 x 10 N.m .C 8 -1 c = 3.00 x 10 m.s 1 u = 931.5 MeV 1.0078 u 1.0086 u 2 r Patm=101.325 kPa -1 -1 cice = 2000 J.kg .K -1 -1 cglass = 840 J. kg . K -1 -1 cwater = 4186 J. kg .K 4 -1 Lf = 33.5 x 10 J.kg Lv = 22.6 x 105 J.kg-1 n = 1.33 n = 1.00
FORMULA SHEET y A sin( 2 ft f t 10dB log sin (m
2 x
I
1 ) 2 W
v ; n 1,2,3,... 2 L v ; n 1,3,5,... 4 L
f n n
f
1 d o
m
d i d o
v
sin m
1 d i
sin 1.22
T 1
E
m / L
I o
f n n
1
)
F
r
2 2 v u 2as
s ut
1
2
at
2 u v s t 2
D
v f
m A
kq
v u at
Q mL....
1 1 P 1 1v12 1 gh1 P 2 2 v 22 2 gh2 2 2
W nc KE PE
r 1.20 10
r 2
Q mcT ;
15
V
L L0 T
W
ln 2
2
kq
1 3
n d ' d ( 2 ) n1
N N 0 e t
P b P t gh
Q=Av
T ( C ) o
o
T(K) = 273 + T( C) f 12 R
7
5 9
( F 32) o
PHYSICS 1
2nd OPPORTUNITY
APFSG1A”
“
2016 – JUNE/JULY JUNE/JULY - EXAM
VAAL UNIVERSITY OF TECHNOLOGY
Faculty:
APPLIED & COMUTER SCIENCE
Department:
PHYSICS AND NDT
Subject:
PHYSICS 1 (1 Opportunity)
CODE
APFSG1A
Duration:
2 Hours
Examiner:
Mr. F.P. NEMALILI
Moderator:
Dr. V. NOLTING
Total marks:
108
st
Full marks:
*Requirements:
*Instructions:
Signature Examiner: Signature Moderator:
Answer all questions
of
Date:
of
Date:
8
100
PHYSICS1 - APIFSG 1A
nd
MEMORANDUM
2
OPP EXAM – JUNE/JULY JUNE/JULY 2016
QUESTION 1 [3X10 = 30] 1.1 1.2 1.3 A A A
1.4 C
1.5 C
1.6 C
1.7 B
1.8 B
1.9 B
1.10 D
QUESTION 2 [25] 2.1.
Total internal reflection: When light travels from optical denser medium to an optical less dense medium and the angle of incidence is larger than the critical angle, light is reflected back into the medium. [3]
2.2.
[10] a) b) c)
A=5m λ = 2.5 m
T=1s f = = 1/T=1/1=1 Hz v = fλ= (1)(2.5) fλ= (1)(2.5) = 2.5 m/s
d) e)
T T 075 N 2.5 T 0.075 m 1.2 x10 2 l 2 x 2 x y A sin( 2 ft f t ) y 5 sin( 2 t ) 2.5 v
f)
g) 2.3.
I 1 I 60 10 log 1 I 1 1 10 6 W / m 2 I 0 I 0 I n nI 1 n 79432 n 10dB log 109 10 log I I 0 0 1 10dB log
[4]
2.4. If d1 = 19.5 m, then d 2 = 42.0 – 19.5 = 22.5 m, Hence ∆Path = d2 - d1 = 3.0 m, and
v f
345 345m / s 115 115 Hz
3.0m , hence, Path n 3 n(3) n 1 , and the speakers are
vibrating out of phase, Therefore Suzan is standing at a point of destructive interference. That is, she is standing at a quiet spot. [4] 2.5.
s L
1.22
D
D
1.22 L s
9 17 1.22 550 10 4.2 10
1.2 10
17
2.3m
[4]
PHYSICS1 - APIFSG 1A
nd
MEMORANDUM
2
OPP EXAM – JUNE/JULY JUNE/JULY 2016
QUESTION 3 [24]
3.1.
Conservation of Linear Momentum – In an isolated system the total linear momentum of remains constant (conserved). An isolated system system is one for which the sum of the average external forces acting on the system is zero. [3]
3.2. R x 16.0m cos 200 0.0m 12.0m cos350 26.0 cos500 R x 8.2m R y 16.0m sin sin 200 11.0m 12.0m sin sin 350 26.0 sin sin 500 R y 10.3m R R x R y R 2
2
0
8.2m 10.3m R 13.2m 2
2
0
R y 10.3m tan1 tan 51.5 0 South of West 8.2m R x 1
[7] 3.3. 1 1 1 y 0t gt 2 y gt 2 80.0m (9.8m / s 2 )t 2 t 4.04s 2 2 2
Thus the horizontal distance x 0t x 8.0m / s * 4.04 x 32.3m
[4]
3.5 E f E 0
1 2
m f mgh f 2
1
1 2 2 m 0 mgh mgh0 f gR f 2 gR 2 2
f 2 9.8m / s 2 3.0m f 7.67m / s [3] 3.6. a.
P P i
f
m B B m B mW f 0.3k g 65m / s 0.3k g 15k g f
f 1.275 275m / s
[2]
b.
F (m x
B
mW )a x f k (m B mW )a k F N (m B mW )a
2 k (m B mW ) g (m B mW )a a k g a (0.125 125)(9.8m / s 2 ) a 1.225m / s
Thus f 0 2as 0 1.275 275m / s 2 1.225 225m / s 2 s s s 0.664 664m 2
2
2
[5]
10
PHYSICS1 - APIFSG 1A
QUESTION 4 4.1.
MEMORANDUM
nd
2
OPP EXAM – JUNE/JULY JUNE/JULY 2016
[29]
Transfer of heat due to electromagnetic waves.
[2]
4.2. a.
q1
E ne E 1 E 2 k
r 1
2
q2 2
r 2
2 10 6 5 10 6 E ne 9 10 2 2 0 . 52 0 . 02 8 8 E ne 1.12 10 N / C Or E ne 1.12 10 N / C to the Left 2
[4]
b. Vo
kq5
V f
kq5
x1 x2
9.0 10
9
(5 10 10 6 ) 0.5
9.0 10
9
(5 10 106 ) 0.02
90000V 2250000V
W (Vo V f )q2 C (2.34 106 ) (2 106 ) 4.68J
[4]
4.3. a. 1
R8,16, 20
1
1 1 1 1 R20 20 25.3 8 16 R8 R16 1
R9,18
1 1 6 R R 9 18
[4]
1
1 1 Req 4.9 6 25.3 b.
V 8 8 0.5 4V V 16 I 16 I top
4
0.25 A, 16 0.5 0.25 0.75 A
V total V top I top Rtop 0.75 25.3 18.98V [4]
11
PHYSICS1 - APIFSG 1A
nd
MEMORANDUM
2
OPP EXAM – JUNE/JULY JUNE/JULY 2016
4.4. d12
A1 F2
A2
4 F 1
7.85 105 m 2 ,
A2
d 2 2 4
7.85 103 m 2
A1
[4]
F 1 250 7.85 103 25000 N A2 5 7.85 10 7.85 A1
F2
Wload F2 mg m
F 2 g
25000 9.8
2551.02kg
4.5.
d d0 T (23 106 / o C )(2.725 102 m)(100o C 0o C )
6.27 105 m 0.00627cm d new d o d 2.725cm 0.0627cm 2.731cm
[3]
4.6. N(remaining) N(remaining) = 1000-970=30 1000-970=30 nuclei nuclei remaining, remaining, Hence 1 N ln t N o
T1
2
1
30
1
0.058 s ln 60 s 1000 ln 2 ln 2 11.86 s 0.058 s 1
12
[4]
